ITERATIVE STATEMENTS

Definition

Iterative statements (loops) allow a set of instruction to be executed or performed several until condition are met. It can be predefined as in the loop, or open ended as in while and do-while.

Types of Iterative Statements

The For statements

The While statements

The Do-While statements

The For statements

The For statement or for loop is considered as a predefined loop because the number or times it iterates to perform its body is predetermined in the loop’s definition.

The For loop contains a counter whose values determine the number of times the loop iterates. The iteration stops upon reaching the number of times specified in the loop.

The For statements

The general form of the for statement is:

for (initialization; condition; increment)

{

statement_sequence;

}

The For statements

Where: for is a reserve word in C Initialization is an assignment statement that is used

to set the loop’s counter. Condition is a relational boolean expression that

determines when the loop will exit. Increment defines how the loop’s counter will change

each time the loop is separated. Statement sequence may either be a single C

statement or a block of C statements that make up the loop body.

The For statements The for loop continues to execute until the

condition is True (1). Once False (0), program execution resumes

on the statement following the for loop. Note:

Never place a semicolon right after the for header.Never change the value of the for loop’s counter in

side the body of the loop. This will affect the result of the program.

The increment part of the for loop is execute after the first iteration of the loop.

The For statements Example:

Write a program that will print the numbers 1 to 10 using a for statement.

#include<stdio.h>

int x;

main()

{

for (x=1; x<=10; x++)

printf (“%d\n”,x);

getch();

}

12345678910

SAMPLE OUTPUT:

The For statements - Exercise

What will be the output of the following program segment?

#include(stdio.h>

int x, sum;

main()

{

sum = 0;

for (x=1; x<=10; x++)

sum=sum + x;

printf(“The sum of 1 to 10 is &d\n”,sum);

getch(); }

The While statement

The while statement or while loop is an open-ended or event-controlled loop.

The while loop iterates while the condition is TRUE (1).

When it becomes FALSE (0), the program control passes to the line after the loop code.

The While statement

The general form of the while statement is:

while (condition)

{

statement_sequence;

}

The While statement

where:While is a reserved word in CCondition is a relational expression that

determines when the loop will exit. Statement_sequence may either be a single

C statement or a block of C statements that make up the loop body.

The While statement Example:

Write a program that will print the numbers 1 to 10 using while statement.

#include<stdio.h>int x;main(){ x=1; while (x<=10) {

printf (“%d\n”,x); x++;

} getch();}

12345678910

Output:

The Do-While statement

The second type of open-ended or event-controlled loop is the do-while statement or do-while loop.

The general form of the do-while statement is:

do

{

statement_sequence;

} while (condition);

The Do-While statement

Where: While and do are reserved words in CCondition is a relational expression that

determines when the loop will exit.Statement_sequence may either be a single

C statement or a block C statements that make up the loop body.

The Do-While statement

Do-While is a variation of the while statement which checks the condition at the bottom / end of the loop.

This means that a do-while loop “always executes at least once”.

In the do-while loop, when the condition evaluates to TRUE (1), the loop body will be executed, but when FALSE (0), program control proceeds to the next instruction after the do-while loop.

The Do-While statement

Write a program that will get the average of all integers from 1 to 10 using do-while loop.

#include<stdio.h>int x, sum;float average; main(){

sum = 0;x++;do{

sum = sum + x;x++;

}while (x<=10)average = sum / 10.00;printf (“the computed average is %.2f\n”,

average);getch();

}

The computed average is 5.50.

Output: